There is considerable controversy concerning the effects of HIV coat- protein, gp120, upon signal transduction, and in particular upon phospholipase C-linked receptor-mediated events. Partly, this confusion reflects the lack of the confidence that the scientific community has in many of these studies because of uncertainty that the preparations of coat proteins used were actually biologically active. We have prepared recombinant gp120 ourselves from a transfected CHO cell line. SDS-PAGE of our CHO-rgp120 has shown it to migrate with a similar molecular size to negative gp120 indicating it to be suitable glycosylated. We employed two independent tests of biological activity: Dr. D. Benos, University of Alabama confirmed that our gp120 increased expression of an astrocyte cell adhesion molecule. Secondly, our preparations induced p56lck autophosphorylation in THP-1 human monocytes. Thus, when we failed to see other effects of gp120 upon cell signaling, we knew this was not due to our protein preparations being inherently inactive. Our determination that gp120 has no effect upon phospholipase C activity in resting and stimulated T-cells is the first definitive study of its kind that will help focus this field of research in a more appropriate direction.